• Journal of Chest Surgery
• /
• 제36권10호
• /
• pp.711-720
• /
• 2003

배경: 폐암은 근치적 절제술이 가장 좋은 치료법이나 수술 후에 재발한 경우나 수술 시기가 지난 경우에는 항암 화학요법의 중요성이 강조된다. 항암 치료 전에 감수성 있는 항암 화학 치료제가 선별되어진다면 치료 효과를 극대화할 수 있다. 신피막하 분석법은 흉, 복부 종양의 생체 내 검사법으로 중요성이 인정되고 있고 항암 감수성 검사로서도 짧은 기간 내에 판별이 가능한 이점이 있다. 신장은 각종 암세포의 이식 장소로 잘 알려져 있으나 비장이나 간에서의 이식 성적을 비교한 연구는 없는 실정이다. 인체 암세포 이식의 실험방법 중에 비장과 간장에 암 세포주를 이식하였을 경우와 신장에 시행되는 신피막하 분석법에 의한 성장의 차이점 유무를 평가하였다. 대상 및 방법: 인체 폐암 세포주(SW-900 G IV)를 RPMI 1640 (Leibovitz L-15 medium)배지에서 배양하여 fibrin clot으로 만들어 $10^{8}$ 개의 암세포가 포함되도록 한 후 3${\times}$${\times}$3mm의 크기로 Spague Dawely (S.D.) 암컷 쥐의 신, 비장 및 간 피막하에 이식하였다. 이식 후 1일부터 6일간 면역억제를 위하여 cyclosporin-A (80 mg/kg)를 피하투여하였다. 이식 전후 실험동물의 체중 변화, 종양의 성장 여부 및 종양의 크기를 계측하고 병리 조직 검사와 혈청 내 암 표지자 검사를 실시하여 비교하였다. 걸과: 실험 5.D. 쥐의 체중 변화는 대조군이나 실험 군 모두에서 체중 증가가 있었다. 혈청 내 암 표지자의 정량 검사 결과 Cyfra 21-1은 검출되지 않았고, CEA및 NSE는 의미 있는 변화가 없었으며, SCC-Ag이 실험 군에서 유의한 증가가 있었다. 비장에 이식한 폐암 세포주의 성장이 신장 및 간장에 비해 더 증가된 결과를 보였다. 표면적, 두께와 용적 모두가 비장에서 유의한 증가를 나타내었다. 이식 성공률은 신장이 80%, 비장이 76.7%, 간장이 43.3%이었다. 병리학적 검사 결과 신장에는 비교적 둥글게 성장하며 크기는 제일 작았으며 성장 방향이 일정한 모양을 보이는 특징이 있으며 비장은 성장이 잘되어 제일 큰 종양을 형성하나 불규칙한 성장과 위성 종양(satellite tumor)이 빈번히 발견되었으며 현미경적으로는 혈관 신생과 함께 종양 혈전이 발견되었다. 간장은 간 내부로 침투 성장하여 이식 성공률이 가장 저조하며 현미경적 소견은 응고성 괴사와 점액양 섬유성 병변을 가지는 특징을 보였다. 걸론: 이식 성공률은 신장과 비장이 높으나, 성장이 일정하고 계측이 용이한 것은 신장이었다. 혈청 암 표지자는 SCC-Ag이 가장 조기에 반응하였으며, Cyfra 21-1은 조기에 검출되지 않았다. 이상에서 감수성 검사를 위한 종양이식 실험에 이용하기에 가장 적합한 장기는 신장을 이용한 신피막하 이식법으로 생각되며, 조기에 유용한 암표지자 검사는 SCC-Ag 정량법이라고 판단된다.

• 한국정밀공학회지
• /
• 제28권3호
• /
• pp.285-291
• /
• 2011

The error motion of a machine tool spindle directly affects the surface errors of machined parts. The error motions of the spindle are not desired errors in the three linear direction motions and two rotating motions. Those are usually due to the imperfect of bearings, stiffness of spindle, assembly errors, external force or unbalance of rotors. The error motions of the spindle have been needed to be decreased to desired goal of spindle's performance. The level of error motion is needed to be estimated during the design and assembly process of the spindle. In this paper, the estimation method for the five degree of freedom (5 D.O.F) error motions of the spindle is suggested. To estimate the error motions of the spindle, waviness of shaft and bearings, external force model was used as input data. And, the estimation models are considering geometric relationship and force equilibrium of the five degree of the freedom. To calculate error motions of the spindle, not only imperfection of the shaft, bearings, such as rolling element bearing, hydrostatic bearing, and aerostatic bearing, but also driving elements such as worm, pulley, and direct driving motor systems, were considered.

• Imaging Science in Dentistry
• /
• 제37권1호
• /
• pp.53-59
• /
• 2007

Purpose : Bone mineral density (BMD) and bone microarchitecture are important determinants for bone strength. Recently micro-CT have provided possibilities for measuring a variety of structural indices to characterize bone microarchitecture. The objective of this study was to compare the BMD and micro-CT parameters with Young's modulus calculated by finite element analysis (FEA) for the evaluation of bone strength. Materials and Methods Bone specimens were obtained from the 18 female rabbits aged 16 weeks. Of those, 36 samples (right and left femur) were selected for 3D micro-CT analysis $(ANT^{TM},\;SKYSCAN,\;Belgium)$ and BMD by PIXlmus 2 (GE Lunar Co. USA). Five microstructural parameters of micro-CT, such as trabecular thickness (Tb.Th), bone specific surface (BS/BV), percent bone volume (BV/TV), structure model index (SMI) and degree of anisotropy (DOA) were studied. Young's modulus was obtained by software program (ANSYS 9.0, ANSYS Inc, Canonsburg, PA) based on micro-CT three dimensional images. Results : Young's modulus assessed by FEA correlated significantly with Tb.Th, BV/TV, BS/BV and SMI respectively. Young's modulus showed higher correlation with these rnicrostructural parameters of micro-CT than BMD. Microstructural parameters except DOA showed significant correlations within the examined group. Conclusion The microarchitectural parameters o( micro-CT and BMD represented some informations in the evaluation of bone strength assessed by FEA.

• 대한조선학회논문집
• /
• 제51권5호
• /
• pp.409-418
• /
• 2014

Simulation of flow past a complex marine structure requires a fine resolution in the vicinity of the structure, whereas a coarse resolution is enough far away from it. Therefore, a lot of grid cells may be wasted, when a simple Cartesian grid system is used for an Immersed Boundary Method (IBM). To alleviate this problems while maintaining the Cartesian frame work, we adopted an Adaptive Mesh Refinement (AMR) scheme where the grid system dynamically and locally refines as needed. In this study, We implemented a moving IBM and an AMR technique in our basic 3D incompressible Navier-Stokes solver. A Volume Of Fluid (VOF) method was used to effectively treat the free surface, and a recently developed Lagrangian Dynamic Subgrid-scale Model (LDSM) was incorporated in the code for accurate turbulence modeling. To capture vortex induced vibration accurately, the equation for the structure movement and the governing equations for fluid flow were solved at the same time implicitly. Also, We have developed an interface by using AutoLISP, which can properly distribute marker particles for IBM, compute the geometrical information of the object, and transfer it to the solver for the main simulation. To verify our numerical methodology, our results were compared with other authors' numerical and experimental results for the benchmark problems, revealing excellent agreement. Using the verified code, we investigated the following cases. (1) simulating flow around a floating sphere. (2) simulating flow past a marine structure.

• Structural Engineering and Mechanics
• /
• 제56권6호
• /
• pp.899-916
• /
• 2015

Upgrading or strengthening of existing reinforced concrete (RC) infrastructure is an emerging demand nowadays. Near Surface Mounted (NSM) technique is very promising approach for flexural strengthening of RC members. However, premature failure such as concrete cover separation failure have been a main concern in utilizing this technique. In this study, U-wrap end anchorage with carbon fiber reinforced polymer (CFRP) fabrics is proposed to eliminate the concrete cover separation failure. Experimental programs were conducted to the consequence of U-wrap end anchorage on the flexurally strengthened RC beams with NSM-steel. A total of eight RC rectangular beam specimens were tested. One specimen was kept unstrengthened as a reference; three specimens were strengthened with NSM-steel bars and the remaining four specimens were strengthened with NSM-steel bars and U-wrap end anchorage using CFRP fabrics. A 3D non-linear finite element model (FEM) was developed to simulate the flexural response of the tested specimens. It is revealed that NSM-steel (with and without end-anchors) significantly improved the flexural strength; moreover decreased deflection and strains compared with reference specimen. Furthermore, NSM-steel with end anchorage strengthened specimens revealed the greater flexural strength and improve failure modes (premature to flexure) compared with the NSM-steel without end anchorage specimens. The results also ensured that the U-wrap end anchorage completely eliminate the concrete cover separation failure.

• Tribology and Lubricants
• /
• 제35권2호
• /
• pp.99-105
• /
• 2019

This study presents an experimental investigation of the wear and oxidation of the bristles of a brush seal in a super-heated steam environment. We construct a model reflecting normal force and radial interference to predict the amount of wear. To monitor the volume loss of the bristle induced by the swirl phenomenon of the rotor, we measure the clearance between the rotor and the brush seal by using a non-contact 3-D device. We calculate the area by using the area-wise measurement method. Considering the obvious brush seal wear variables, we use two disks with different roughness($Ra=0.1{\mu}m$ and $100{\mu}m$) to determine the effect of roughness on wear. Considering an actual steam turbine, we utilize a steam generator and super-heater to generate a working fluid (0.95MPa, 523.15K) that has high kinetic energy. We observe the abrasion of the bristles in the hot steam environment through a scanning electron microscope image. This study also conducted energy dispersive X-ray (EDX) analysis for a qualitative evaluation of local chemistry. The results indicate that the wear and elimination of bristles occur on the disk with high roughness, and the weight increases due to oxidation. Furthermore these results, reveal that the bristle oxidation is accelerated more under super-heated steam conditions than under conditions without steam.

• Structural Engineering and Mechanics
• /
• 제83권4호
• /
• pp.551-561
• /
• 2022

In this paper, the effect of fire conditions according to ISO 834 standard on the behavior of carbon fibre-reinforced plastic (CFRP) reinforced steel beams coated with gypsum-based mortar has been investigated numerically. To study the efficiency of these beams, 3D coupled temperature-displacement finite element analyzes have been conducted. Mechanical and thermal characteristics of three different parts of composite beams, i.e., steel, CFRP plate, and fireproof coating, were considered as a function of temperature. The interaction between steel and CFRP plate has been simulated employing the adhesion model. The effect of temperature, CFRP plate reinforcement, and the fireproof coating thickness on the deformation of the beams have been analyzed. The results showed that within the first 120 min of fire exposure, increasing the thickness of the fireproof coating from 1 mm to 10 mm reduced the maximum temperature of the outer surface of the steel beam from 380℃ to 270℃. This increase in the thickness of the fireproof layer decreased the rate of growth in the temperature of the steel beam by approximately 30%. Besides excellent thermal resistance and gypsum-based mortar, the studied fireproof coating method could provide better fire resistance for steel structures and thus can be applied to building materials.

• Structural Engineering and Mechanics
• /
• 제85권5호
• /
• pp.593-605
• /
• 2023

This work presents a comparison between analytical and finite element analysis for bending of porous sandwich functionally graded material (FGM) plates. The plate is rectangular and simply supported under static sinusoidal loading. Material properties of FGM are assumed to vary continuously across the face sheets thickness according to a power-law function in terms of the volume fractions of the constituents while the core is homogeneous. Four types of porosity are considered. A refined higher-order shear with normal deformation theory is used. The number of unknowns in this theory is five, as against six or more in other shear and normal deformation theories. This theory assumes the nonlinear variation of transverse shear stresses and satisfies its nullity in the top and bottom surfaces of the plate without the use of a shear correction factor. The governing equations of equilibrium are derived from the virtual work principle. The Navier approach is used to solve equilibrium equations. The constitutive law of the porous FGM sandwich plate is implemented for a 3D finite element through a subroutine in FORTRAN (UMAT) in Abaqus software. Results show good agreement between the finite element model and the analytical method for some results, but the analytical method keeps giving symmetric results even with the thickness stretching effect and load applied to the top surface of the sandwich.

• 한국해안·해양공학회논문집
• /
• 제34권6호
• /
• pp.290-302
• /
• 2022

본 연구에서는 월파가 발생하는 호안을 대상으로 보강방안 적용시 월파저감과 호안전면에서의 수위변화에 대해 검토하였다. 연구결과 단면실험의 경우 보강조건에 따라 약 70% 이상의 월파저감효과가 나타났으며 평면실험과의 비교에서 약 4배 이상의 월파량이 증가하는 것으로 분석되었다. 호안전면 수위는 저마루 구조물 미 설치시 평균수위가 감소하였으며 저마루 구조물 설치조건에서는 상승하는 경향이 나타났다. 평면실험과의 비교에서 저마루 구조물 미설치시 𝜂/H'₀가 약 0.5~0.6배의 차이가 나타났으며 저마루 구조물 설치 후에는 최대 5.5배 증가된 값이 발생하였다. 따라서, 단면실험을 통한 월파량 및 수위상승 검토시 과도한 결과가 발생될 수 있으므로 이에 대한 면밀한 검토가 필요할 것으로 판단된다.

• 대한치과보철학회지
• /
• 제59권1호
• /
• pp.18-26
• /
• 2021

목적: 일반적으로 총의치는 환자의 구내에서 제거 시 물에 담가 보관하도록 설명하는데, 수중에서의 총의치의 보관이 상온의 공기중에서 총의치를 보관하는 것과 비교해 체적 안정성에 장점이 있는지에 대한 연구는 부족하다. 본 연구는 의치의 올바른 보관 방법을 규정하는 데에 참고가 될 수 있도록, 수중에서 보관하는 경우와 공기중에 보관하는 경우에 의치상의체적 변화량과 양상을 평가하는 것을 목적으로 한다. 재료 및 방법: 초경석고로 제작한 주모형을 디지털 스캔하여, computer-aided design (CAD) 소프트웨어를 이용해 총의치 의치상을 디자인하고, 3D printing 기법을 이용하여 상악과 하악 각 6개의 시편을 제작하였다. 이를 매몰한 후 열중합 방식으로 온성하여 제작한 레진의치상을 상악과 하악 각 3개씩 그룹 A와 그룹 B로 나누었다. 그룹 A는 상온의 공기중에서 보관되었고, 그룹 B는 상온의 물에 담가 보관하며 24시간 간격으로 28일 동안 스캔하여 stereolithogrphy (SLA) 파일로 저장하였다. 이를 분석하여 한달 간의 체적변화를 측정하였고, best-fit 알고리즘을 이용하여 중첩시켜 3차원 비교 컬러맵을 이용하여 의치상 인상면의 변화 양상을 관찰하였다. 측정한 값은 Kruskal-Wallis test를 이용하여 분석하였다. 결과: 보관방법에 상관없이 총 체적에는 유의한 변화가 없었으나, 공기 중에서 보관한 의치상의 경우 상악 구개부와 하악 구치부 설측 변연에서 조직과 멀어지는 방향으로, 상악 결절부와 하악 후구치 삼각 융기 부위에서는 조직을 압박하는 방향으로 통계적으로 유의한 변화를 보였다. 결론: 수중에서의 의치 보관은 공기중에서의 의치 보관에 비해 의치상 인상면의 변화가 적게 나타났다.